A member of Demon Slayer Corps. She is addressed as the ‘Hashira’, which is the highest rank among all the demon slayers. She is also the current ‘Insect Hashira’.
She is able to kill man-eating demon with toxin created by using wisteria flowers—one of the very few things that demons are vulnerable to.

Shinobu is a beautiful girl. In Zenitsu’s word, she can「make a living by her beauty」. She wears a butterfly ornament at the back of her head, and an elegant haori with a butterfly pattern, all of which accentuates her beauty.

Character

She is one of the most powerful swordsmen, an excellent battle commander and a good trainer. She has played an important role in helping Tanjiro and his peers learn breathing styles.
She is proficient in medical and pharmacy and very good at logistic support, such as taking care of injured demon slayers and mentoring her TsugukoKanao Tsuyuri, etc. It can be said that she is the indispensable woman in Demon Slayer Corps.

She is always having a smile on her face. She has a nice and gentle pet phrase:「humans and demons should be friends」and seems to be a pacifist who likes talking about『reconciliation』with demons.
However, her『reconciliation』requires demons to make atonement for their sin by receiving torture such as having eyes and guts pulled out. Even immortal demons cannot accept the harsh terms. So her reconciliation is actually a kind of provocation.
She always talks about these harsh terms with demons in a beaming face, which indicts that Shinobu may not be in a normal state of healthy mind.

The reason why Shinobu acts this way has a lot to do with her biological sister Kanae Kochou.
Kanae and Shinobu’s family were slaughtered by demons when they were little. And they themselves were barely spared from death as they were saved right in the nick of time by the arrival of a demon slayer.
The Kochou sisters were left all by themselves and later joined Demon Slayer Corps. Kanae was a kind girl who even sympathized with demons.
「humans and demons should be friends」used to be the sister’s pet phrase.
However, the kind and highly-talented sister Kanae was fatally wounded by demons and died in Shinobu’s arms.
Shinobu’s heart was torn by anger and grief as she watched her beloved sister ruthlessly killed by a demon.

Before dying, Kanae tried to convince her sister to leave the Demon Slayer Corps to live out a normal life, but her sister did not quit and eventually became a Hashira.
Shinobu smiled a lot because her older sister liked her smile, which meant that it was not a genuine smile.
Beneath the serene smile, there were torrential「rage」and 「hatred」against demons.
Shinobu hid her hatred against demons and pursued her sister’s ideal in a very complex mood. However, she was indeed worn out by the burden of the mask of fake smile.
The above history turned Shinobu into a person who talked about reconciliation with demons in a gentle face, while the way of reconciliation was to torture demons brutally.

Therefore, Tanjiro who had a soft spot for demons became the one to whom she entrusted her ideal.

And, extra edition of the manga which portrayed Kanae’s story while she was alive, described how Kanae and Shinobu sisters met Kanao Tsuyuri who later became Shinobu’s Tsuguko.

At that time, Shinobu was very different from what she looked like in the mainstream story; she frowned a lot, put on a wry face a lot and barely smiled. She acted boldly, for example when she noticed a nameless girl (later known as Kanao ) being dragged along with a leash by a man, she『flung money in the air to distract the man, grabbed the rope he released and ran off with the nameless girl』. She was shown to be serious about things and have a more straightforward demeanor. Those were the natural disposition of Shinobu.
And, the elegant haori with a butterfly pattern she wears in the mainstream story once belonged to Kanae. So shinobu probably wears this haori as a memento of her sister.

Ability

Physical ability

She admits that「she might be the only swords-lady among the Hashiras who can’t cut a demon’s head off」. She may have the weakest swing strength, however, she also displays powerful thrust and stab strength, as the other Hashiras note that a single thrust from her sword could easily pierce a stone in half. And her thrusting speed is also noted to be even faster than「the Seventh Style :Piercing Rain Drop」of Water Breathing.
Yet, Shinobu ranked bottom in the Hashira arm wrestling contest, while a woman who has a special muscle composition with a density eight times that of a regular human ranked in the 3rd place. It was not that Shinobu was weak, but that Mitsuri Kanroji, as a woman was abnormally strong.

Full Focus Breath Breath of the Insect

Shinobu as a short-figured female might not have enough strength to cut off a demon’s head. By using the unique and marvelous ‘Breath of the Insect’, she fully utilizes her sword that is coated with poison.

Poisonis the most powerful weapon of Shinobu who cannot cut a demon’s head off.
Normally, a demon can be killed by only two methods: exposure to sunlight and decapitation by the Nichirin Sword. Shinobu succeeds in killing demons by a kind of toxin she made out of Wisteria flower.
She coats her Nichirin Sword with the toxin and alters the mixture and composition of the toxin to attack demons differing in strength and nature. Due to this unique tactic, Shinobu is sometimes addressed as the「poison lady」.

Shinobu adjusted other breath styles to develop her own unique style. Her breathing style was branched out from her sister’s “Flower Breathing”, which itself is branched out of the Water Breathing. Therefore, like Inosuke, her techniques were not named in「a numerical order」.

Dance of the Butterflies: Frolic
The technique Shinobu used to kill 『Older Sister Spider Demon』in the mission in Mount Natagumo.
The 『Older Sister Spider Demon』who has slaughtered quite a few demon slayers are not even able to detect any movement before falling down.

Dance of the Bee Sting: Mere Fluttering
Shinobu dashes at her target at an incredible speed and uses the momentum of her speed to then strengthen her single thrust into her opponent. This technique can even pierce the skulls of the Upper Moons.

Dance of the Dragonfly: Compound Eye Hexagon
A technique used to inject the opponent with multiple doses of toxin. 「dragonfly」means TONBO in Japanese.

Dance of the Centipede: Hundred-Legged Zigzag
A burst of random and speedy movements which are powerful enough to crumble a wooden baseboard.「Centipede」means MUKADE in Japanese.

Equipment

As a member of the Demon Slayer Corps, shinobu is deployed with uniform and Nichirin Sword.

Shinobu’s Nichirin sword was made by Tetsuchin Tetsujikoura the chief of Swordsmith Village. It resembled the shape of thin sword, and the blade was cut thin in the middle leaving the point and the part adjacent to the handle the normal size. There was not enough room for engraving four kanji on one side, so 「DEMON」「DESTROY」were engraved separately on front and back. It has an exquisite butterfly-shaped handguard. Shinobu formulated her poison inside her scabbard and no one known how it was done but herself and her swordsmith. (according to the “It’s time for a Taisho secret” corner, 20th episode of the Kimetsu no Yaiba anime).

Besides, Shinobu hid a small knife (it was not known whether it was a Nichirin sword or not) in her straw sandals.

Uniform

Shinobu wears the standard Demon Slayer uniform- a dark straight-lined black jacket, just made a little smaller to fit her size.
She is also wearing a haori with a butterfly wing pattern as a memento of her sister.

Actually, like Mitsuri Kanroji, Shinobu had received a sexier version of the standard uniform from the eyeglass jerk. Instead of wearing it, Shinobu spilt gasoline on the uniform and burnt it in front of Maeda. Since then, the girls serving Shinobu always had matches and gasoline around when dealing with the eyeglass jerk.

By the way, though short-figured, Shinobu had an hourglass figure. The sexy uniform might actually fit her well.

Butterfly Estate is a manor deployed to the Hashira, and often used as a recovery base for injured demon slayers.
It also accommodates people (mostly female) whose families are killed by demons. And girls living inside also wear butterfly headdresses. And together with young female demon slayers who are not power enough to go front lines, young girls living in the estate work as nurses.

※Illustration above is Butterfly Estate’s main member.

Digression

According to the “It’s time for a Taisho secret” corner in the anime, Shinobu was not fond of furry animals such as dogs and cats.

With the height of 151cm and weight of 37kg, her BMI index would be 16. And a standard BMI index of 151 cm in height indicates a weight of 50kg. So Shinobu’s is quite underweight. However, even in modern times, there are some models or artists who have similar body data, so it's not impossible. Moreover, low BMI does not necessary indicate an underweight body status when the body fat rate is normal.
Besides, in Taisho era when the story happened, compared with modern times, had less nutritious. Western food of high calorie and high protein was considered as high-end and rare. Yet, some readers think Shinobu keeps an abnormally low weight for a reason. This point is not mentioned in comic so let’s just leave it here.

Gaiden

Tomioka Giyu Gaiden was published in the 18th issues of Weekly Shonen Jump on 1st April, 2019 when the animation was airing.
The author was Ryoji Hirano.
As the name suggests, Tomioka Giyu is the protagonist. And the story was about a demon incident also involving both Giyu and Shinobu that occurred shortly after Tomioka Giyu’s encounter with Tanjiro and Nezuko.